Method of making artificial teeth



Patented July 12, 1949 METHOD oF MAKING ARTIFICIAL 'IEE'IHar .i

Reiner W. Ernie, ,chic-ago, In., vassigner.; to Austenal` Laboratories,Incorporated, `New York, N. Y., a corporation of NewYork` ApplicationJanuary 10, 1947, Serial-No. '721,407V 1 This :invention relates, ingeneral, to the art of: making. articial teeth, and has particularrelation to an improved method of forming the ridge laps and removingthe sprues from the While the particular embodiment of the in,-ventionwwhich I shall describe hereinafter in -connection `with thedrawing is adapted for use `in. making` plastic or synthetic` resin-liketeeth,

it is `to be vunderstood that it is not limited to such4 use but may beemployed for all similar purposes, as suitable or desired.

- One of: the main objects of the present invention isto provide animproved method with which problems heretofore encountered in makingartifciallteeth `and like articles are eliminated. i Anotheruobject ofthe invention is to provide 'for forming` the ridge lap and removing thesprue in a manner which will lend itself to quantity production` andautomatic or machine handling,

`and which will permit low labor costy andulow `capital investment.

Another object` of the invention is to provide amethodiofthe classdescribed in whichthe ridge flap` is. cut into the tooth simultaneously.with the removal of.` the sprue from the tooth bymilling `or; cuttingthrough the mold: body in which the toothsfisiformed `and through thebody of the tooth at the ridge lap. i

Another object. of the invention is to provide .ai method of the classdescribed which comprises forming tooth cavities and sprue channels in a`moldrbody with the` tooth cavities in line mesially.- `distallyv witheach `other and having ridge laps inalignmenttmolding teeth: andconnected sprues the tooth cavities and sprue channels, and

with the molded teeth in the mold body milling through the mold body andthrough the teeth at the aligned ridge laps with a milling cutter to theshape of the ridge laps to remove the pl'ues from the teeth and,simultaneously, to cut 4 claims. (c1. iss-55.1) l

view Vthrough the` toothmoldfat substantially right tangles. to `Figure1 and; showing. the operation ofthe milling cutter in milling; through,the,` mold bodyy and through the. teeth to 'removethe sprues from theteeth and,` simultaneouslyeutthe ridge laps into the teeth. l

Referring now tothe drawing, the tooth mold shown-at l `may be formed,for example, fofplnster of Paris, gypsum investment, Tamastone, or lowfusing metal `or` `alloy in the manner more fully disclosed in the`previously identified copending application of RoyxC.4 Feagim or of anyother suitable material and `ingany othensuitable manner.

.. Where the mold body lis formedof plasterlike material and the teethare formed` of resinlike material,` the poreslof the m'old body may besealedwithmaterial that will not react deleteriously with the resin-likematerial and of a character tov prevent, seepage of` the `resin-like'material' intovthel moldbedy. This, of course, may` he varied .loromitted, according to the material of the mold body and the toothmaterial. The moldzbody I@ has tooth. cavities 2 and sprue channelsopeningfinto the ridge lap ends .therefof. The ridge lap `ends of thetooth cavities 2 are shown at 4. The surfaces of thecavities 2 arepreferably uninterrupted and free `of. parting lines. i

-Where there are a plurality of tooth cavities 2 as shown in thedrawing, they are preferably aligned mesially-distally with` each other,with the ridgelap `ends 4 in alignment as shown in Figure 1. Thisalignment may be secured, for example,by using metalmaster teeth havingattached metalshanks attached to'a base sprue, withthe ridge `laps ofthe master teeth equidistant from the basesprue. Thefparticular mannerof obtaining this alignmenttmay-vary widely, and therefore `it has notbeen-:shown intdetail inthe present application, l

Upon completion of the mold I the tooth material is introduced into thetooth cavity 2 through the spine-channels v3, and the teeth 5 and theirconnected sprues E are formed in the cavities 2 and channels. The ridgelaps of the teeth are shown at. 4, asv previously indicated. The teeth.,li` and. their-connected sprues 6 may be formed of plastic or syntheticresin-like material.

After the teeth are cured or otherwise nished, they are ready to beremoved from the mold l. Since the teeth are lined up carefully in orderthat the ridge laps may be in a direct line with each other, a suitablemilling cutter, shown at TI and shaped at 8, as indicated in Figure 2, tthe shape of the ridge laps 4 oi the teeth may be used to mill throughthe plaster-like mold I and the tooth material in order to remove theteeth from their sprue-s 6 and, at the same time, cut theedesired ridgelaps 4 into the teeth. The milling cutter 1 is carried by and rotateswith a rotating shaft 9, as shown in Figure 2v. It may be positioned,for example, as shown in Figure 1, and moved toward the left as indiycated by thearrow l0 in a direction and :along 'a path to remove thesprues 6 from the teeth 5 and, simultaneously, to cut the ridge laps 4into the teeth. This leaves the nished teeth 5 in the plaster-like orother mold body I' separate froml each other and from the plaster-likeYor other material formed in the sprue channels 3.

Any suitable knock-out device may be used to separate the plaster-likeor other mold material from the surrounding metal iiask (not shown).After removal of the mold Afrom the flask it may then be placed underpressure of some typerto break the teeth away from the plaster or othermold material. The teeth may then `be rolled in a suitable containercontaining Water or any suitable liquid medium to separate or washtraces of plaster from them. YThe teeth Will then be free from theplaster mold and will be without the desired polish. i'

On a production basis, polishing may be accomplished in a suitabletumbling barrel ordinarily used ior deburring and polishing plastic andmetal articles. AThis barrel may be of hexagonal or octagonal shape, ormay contain any 'suitable material which acts to provide a polishing ordeburring action. The use of Wooden chips are'preferred for thisoperation because they may be separated easily from the teeth aftercompleting the polishing.

The embodiment of the invention shown in the `drawing is forillustrative purposes only, and it is to be expressly understood thatsuch drawing and the accompanying specification are not to be construedas a denition of the lilits `or scope of the invention, reference beinghad to the appended claims for that purpose.

I claimt 1. The method of making artificial resin teeth, which comprisesforming ina monolithic plasterlike mold a plurality of tooth cavities inline -vmesially-distally with each other and* having ridge lap formingportions in alignment and sprue channels opening into saidcavities froma surface of the mold, each mold cavity having a unitary anduninterrupted internal mold surfaceefree of a parting line `for formingthe surfaces of the teeth, introducing the resin material into the theteeth and simultaneously to cutethe ridge laps into the teeth, andthereafter removing the plaster-like mold material from the teeth.

4 2. The method of maleing an articial resin tooth, which comprisesforming in a monolithic plaster-like moldea tooth cavity having a ridgelap forming portion and asprue channel opening Y into the cavity from asurface of the mold, the mold cavity having a unitary and uninterruptedinternal mold surface free of a parting line for forming the surfaces ofthe tooth, introducing the resin material into the mold cavity and sprueY channel and molding the tooth in position with the tooth and ridge lapcompletely embedded in y the mold body and inaccessible from the outsideof the mold, milling, while the molded tooth is embedded in the moldbody, through the plasterlike mold body and through the tooth at theridge lap to remove the sprue from the tooth and simultaneously to cutthe ridge lap in the tooth, and thereafter removing the plasterflikematerial from the tooth.

3. The method of making articial teeth, which, comprises forming in amonolithic mold a plur-ality of tooth cavities in line mesially-distallywith each other and having ridge lap forming portions in alignment andsprue channels opening into said cavities from a surface of the mold,each mold cavity having a unitary and uninterrupted internal moldsurface free of a parting,"

line for forming the surfaces of the teeth, introducing the toothmaterial into the mold cavities i and sprue channels and molding theteeth in posi- Ytion with the teeth and ridge laps completely embeddedin the' mold body and inaccessible fromVV outside the mold, milling,while the molded teeth are embedded in the mold body, through the moldbody and through the teeth at the ridge lap and along the aligned pathof the ridge laps to remove the sprues from the teeth and simultaneouslyto cut the ridge laps into the teeth, and thereafter removing the moldmaterial from the teeth.

4. The method of making an artiiicial tooth which comprises forming in amonolithic mold a tooth cavity having a ridge lap forming portion and asprue channel opening into the cavity from a surface of the mold, themold cavity having a. unitary Yand uninterrupted internal mold surfacefree of YYa parting line for forming the surfaces cessible' from theoutside of the mold, milling,

while the molded tooth is embedded in the mold body, through the moldbody and through the tooth at the ridge lap to remove the sprue fron;the tooth and simultaneously to cut the ridge lap in the tooth, andthereafter removing the mold body material from the tooth.

REINER W. ERDLE.

REFERENCES CITED The following referenlces are'of record in the le ofthis patent:

UNITED STATES PATENTS Number y Name Date 2,345,305 Thornton Mar. 28,19442,386,697 Lynch Oct. 9, 1945 2 392,929 Lee Jan. 15, 1946

